Polylactams such as poly-2-pyrrolidone (Nylon-4) and polycaprolactam (Nylon-6) are produced by the anionic (alkaline-catalyzed) polymerization of the lactam. The catalyst is believed to comprise a lactamate produced by the reaction of a lactam with an alkali metal, or quaternary ammonium hydroxide, or a source of alkali or alkaline earth metal, such as the hydroxide or alkoxide. The reaction product is believed to be a lactamate, e.g., a salt such as potassium pyrrolidonate, the product of the reaction between potassium and 2-pyrrolidone, ##STR1## the salt consists of a cationic species such as K.sup.+, Na.sup.+, Ca.sup.++, NR.sub.4.sup.+, etc., depending upon the source of the catalyst, and an anionic species which may be a pyrrolidonate ion, a caprolactamate ion, etc., depending upon the choice of lactam. Polymerization initiators and/or activators are also present during the polymerization reaction.
The macrocyclic polyethers are neutral compounds containing 4-20 oxygen atoms each separated from the next by two or more carbon atoms. Macrocyclic polyethers have been found to form stable complexes with salts of alkali metals and other metals and ammonium salts; "Macrocyclic polyethers and their complexes", C. J. Pederson et al, ANGEW, CHEM. Internat. Edit., Vol. 11, page 16, (1972); and U.S. Pat. Nos. 3,562,295 and 3,687,978. The macrocyclic polyethers are believed to form salt-polyether complexes in which the cation is encircled by the oxygen atoms of the polyether ring and is held there by the electrostatic attraction between the cation and the negative ends of the CO dipoles. Since the stereo models of macrocyclic polyethers give a crown-like appearance, they are commonly designated as N!-crown-M polyethers, wherein N is the total number of atoms in the polyether ring and M is the number of oxygen atoms in the polyether ring.
The crown polyethers ranging in size from cyclic tetramers of ethylene oxide ( 12!-crown-4) and propylene oxide ( 16!-crown-4) to 60-membered polyether rings (dibenzo 60!-crown-20) have been reported. The most effective complexing agents are said to be found among those polyethers containing 5-10 oxygen atoms each separated from the next by two carbon atoms.